Question 19M.3.SL.TZ1.a.ii
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ1.a.ii |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Deduce | Question number | a.ii | Adapted from | N/A |
In an experiment to measure the acceleration of free fall a student ties two different blocks of masses m1 and m2 to the ends of a string that passes over a frictionless pulley.
The student calculates the acceleration a of the blocks by measuring the time taken by the heavier mass to fall through a given distance. Their theory predicts that and this can be re-arranged to give .
In a particular experiment the student calculates that a = (0.204 ±0.002) ms–2 using m1 = (0.125 ±0.001) kg and m2 = (0.120 ±0.001) kg.
Deduce the value of g and its absolute uncertainty for this experiment.
[2]
g = 9.996 «m s−2» OR Δg = 4.20 «m s−2» ✔
g = (10 ± 4) «m s−2»
OR
g = (10.0 ± 4.2) «m s−2» ✔
Award [1] max for not proper significant digits or decimals use, such as: 9.996±4.178 or 10±4.2 or 10.0±4 or 10.0±4.18« m s−2 » .
Many average candidates did not use the correct number of significant figures and wrote the answers inappropriately. Only the best candidates rounded out and wrote the proper answer of 10±4 ms−2. Some candidates did not propagate uncertainties and only compared the average calculated value with the known value 9.81 ms−2.
